NetBSD, for When Portability and Stability Matter

"In keeping with the metaphor, NetBSD's claim to fame is its high portability — it will run on more than 50 hardware platforms ranging, from the Commodore Amiga to PlayStation 2 to everything in between. If you can get your hands on the hardware, there is probably a NetBSD port available for it. This wide portability has gained NetBSD the reputation of being an ideal operating system for research environments. Organizations with older or marginalized or just plain unusual hardware systems can continue to make use of them for present-day work by installing NetBSD. "Story